PB1772: HIGH SLIT2 LEVELS ARE ASSOCIATED WITH GMP LIKE AML AND TREATMENT WITH RECOMBINANT SLIT2 INHIBITS LEUKEMOGENESIS
Authors: Luise Araujo de Albuquerque Simoes, Isabel Weinhäuser, Diego Antonio Pereira-Martins, Cesar Alexander Ortiz Rojas, Lucio Henrique Pinheiro, Thiago Mantello Bianco, Rita de Cassia Cavaglieri, Eduardo Magalhaes Rego
Journal: HemaSphere (2023)

Topic: 3. Acute myeloid leukemia - Biology & Translational Research Background: Despite recent progress in the treatment of AML, the overall survival for elderly patients remains dismal. Concerns regarding the overall fit of elderly individuals to tolerate intensive chemotherapy schemes have motivated the development of non-intensive therapies. The Slit Guidance Ligand 2 (SLIT2) gene encodes for a glycoprotein which has been shown to play key roles in different physiological processes. In leukemia, its high expression was associated with better overall survival (OS). Previously, we demonstrated that the soluble factor SLIT2 display tumor-suppressive functions with low cytotoxicity in certain AML subtypes (Weinhäuser et al., 2020 - 10.3390/cancers12113134), highlighting its therapeutic potential. Aims: Given these evidences, here we decided to further investigated the role of SLIT2 in AML. Methods: In the present study, a principal component analysis using transcriptomic analysis comparing patients of TCGA with the highest versus lowest levels of SLIT2, revealed patients with SLIT2low being associated with increased expression of genes related to leukemogenesis, such as HOXA10/HOXA7, while AMLs with SLIT2high were correlated with the terms “CELL_CYCLE_CONTROL” and “POSITIVE_REGULATION_OF_APOPTOSIS”. Results: Deconvolution analysis on patients with high and low SLIT2, showed an accumulation of leukemia stem-progenitor cell (LSPC)-quiescent compartment in the SLIT2low. The distribution of AML subtypes (according to Zheng et al., 2022 - 10.1038/s41591-022-01819-x), SLIT2Iow appear to be associated with a higher percentage of the primitive AML subtype, which is enriched for LSPC (40%), while patients with SLIT2high showed a GMP-like profile (37%), associated with good prognosis in AML. Since SLIT2 is a soluble factor, we measured the level of SLIT2 in plasma samples isolated from BM aspirates of adult AML patients at diagnosis who were treated with intensive chemotherapy at the Instituto do Câncer do Estado de São Paulo, Brazil and healthy donors (HD). About 83% (n=43 of 52) of AML patients showed a decreased concentration of SLIT2 in comparison with HD. Additionally, outcome analysis indicated that patients with a high concentration of SLIT2 were associated with better OS compared to patients with SLIT2low concentration. We next wondered if exogenous administration of SLIT2 peptide would exhibit anti-leukemic effects in AML models. Ex vivo treatment of primary AML samples with recombinant SLIT2 peptide (50 ng/mL) significantly reduced the cell count and Ki67 detection in AML cells in comparison with the vehicle control, with non-significative changes in the cell viability, supporting the role of SLIT2 as a cytostatic agent in AML. Xenograft mouse model using MV4-11 cells intravenously transplanted into NSGS mice showed that consecutive SLIT2 treatment (single daily dosage; 7 days) significantly delayed the leukemogenesis and reduced the tumor burden in vivo. SLIT2-treated mice displayed increased OS and reduced infiltration of secondary organs in comparison with the vehicle group. Summary/Conclusion: Together, our data demonstrated the role of SLIT2 as a tumor-suppressive protein in AML, with higher SLIT2 concentration in the BM plasma being associated with increased survival. We demonstrated that SLIT2 protein has cytostatic effects on AML cells, delaying in vivo leukemia progression. Altogether, our data highlights the therapeutical potential of SLIT2 in AML, particularly, in situations where intensive chemotherapy schemes are not an option. Keywords: AML, Acute myeloid leukemia, Proliferation